The present invention relates to the preparation of unsaturated fatty acid monovalent and divalent metal salt nutritional supplements from high glyceride content polyunsaturated oils, including marine oils. The present invention particularly relates to fatty acid monovalent and divalent metal salts rich in desirable unsaturated fatty acids such as omega-3, omega-6, and omega-9 fatty acids, including eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), decosopentaenoic acid (DPA), linoleic acid (LA), arachidonic acid (AA), and linolenic acid (ALA).
Certain divalent metals such as calcium, copper, magnesium and zinc have long been recognized as beneficial mineral nutrients for humans and certain companion animals and livestock, such as ruminants, horses, dogs, cats, rabbits, hamsters, birds, fish, and the like. For example, the mineral calcium not only builds and strengthens bones and teeth, it also maintains normal heartbeat and regulates blood pressure. It is also essential for the healthy functioning of the nervous system.
Copper is a key component of many enzyme systems. Copper deficiency is known to cause anemia, diarrhea, bone disorders, neonatal ataxia, changes in hair and wool pigmentation, infertility, cardiovascular disorders, impaired glucose and lipid metabolism and a depressed immune system.
As a positively charged divalent cation, magnesium acts as a calcium antagonist at the cell membrane level which is necessary to maintain normal electrical potentials and to coordinate muscle contraction-relaxation responses. Additionally, magnesium has roles in energy metabolism as a required cofactor for enzymes that catalyze fatty acid synthesis, protein synthesis, and glucose metabolism. Zinc also is essential for protein synthesis, integrity of cell membranes, maintenance of DNA and RNA, tissue growth and repair, wound healing, taste acuity, prostaglandin production, bone mineralization, proper thyroid function, blood clotting and cognitive functions.
A variety of unsaturated fatty acids have been identified as desirable for producing a diversity of nutritional and physiological benefits in humans and lower animals, including companion animals and livestock, and accordingly have attracted attention as nutritional supplements. In certain animals, omega-3 fatty acids for example, have been discovered to promote fertility, promote healthy skin and coat, reduce inflammation, and have other nutritional and physiological properties as well. In humans, it is believed that omega-3 fatty acids such as EPA and DHA support healthy cardiovascular function, are important for visual and neuronal development, support healthy blood levels of cholesterol, triglycerides and very low density lipoproteins, ease the inflammation associated with overuse of joints, and improve carbohydrate metabolism.
Conjugated Linoleic Acids (CLA's) have been discovered to possess a diverse and complex level of biological activity. Anticarcinogenic properties have been well documented, as well as stimulation of the immune system. U.S. Pat. No. 5,914,346 discloses the use of CLA's to enhance natural killer lymphocyte function. U.S. Pat. No. 5,430,066 describes the effect of CLA's in preventing weight loss and anorexia by immune system stimulation.
CLA's have also been found to exert a profound generalized effect on body composition, in particular, upon redirecting the partitioning of fat and lean tissue mass. U.S. Pat. Nos. 5,554,646 and 6,020,378 disclose the use of CLA's for reducing body fat and increasing lean body mass. U.S. Pat. No. 5,814,663 discloses the use of CLA's to maintain an existing level of body fat or body weight in humans. U.S. Pat. No. 6,034,132 discloses the use of CLA's to reduce body weight and treat obesity in humans. CLA's are also disclosed by U.S. Pat. No. 5,804,210 to maintain or enhance bone mineral content.
It is also known that supplementing the diet of livestock with unsaturated fatty acids will alter the livestock fatty acid profile, so that, for example, feeding dairy cows and beef cattle a source of unsaturated fatty acids beneficial to humans will yield dairy and beef products for human consumption enriched with the beneficial unsaturated fatty acids. For example, U.S. Pat. No. 5,143,737 discloses that the unsaturated fat content of milk and meat from ruminant animals can be increased by incorporating the intended unsaturated fat into the diet of the ruminant.
Thus, meat and milk enriched with CLA's and other unsaturated fatty acids can be obtained by supplementing ruminant diets with unsaturated fatty acids such as CLA. Dairy cows and beef cattle fed a source of CLA not only will produce lower fat content dairy and beef products, the products will be enriched with CLA's as well. Dietary supplementation of dairy cows and beef cattle with unsaturated fatty acids beneficial to humans can also be used to displace and thereby reduce the levels of undesirable saturated fatty acids in dairy and beef products.
The beneficial effects produced by unsaturated fatty acids are not limited to CLA's. Other unsaturated fatty acids are disclosed to be useful for treating diabetes (U.S. Pat. No. 4,472,432), heart disease (U.S. Pat. Nos. 4,495,201; 5,541,225 and 5,859,055), prostaglandin deficiencies (U.S. Pat. No. 5,043,328), malaria (U.S. Pat. No. 5,604,258), osteoporosis (U.S. Pat. Nos. 5,618,558 and 5,888,541), cancer (U.S. Pat. No. 5,763,484), immune system function (U.S. Pat. No. 5,767,156), Huntington's Chorea (U.S. Pat. No. 5,837,731) and inflammation (U.S. Pat. No. 5,861,433). The disclosures of the foregoing patents are all incorporated by reference.
It has further been discovered that ruminants fed a source of trans-C18:1 fatty acids will have decreased concentrations of milk fat, hepatic triacylglycerol, and lower incidence of sub-clinical ketosis during early postpartum, and that feeding a source of linoleic (C18:2) fatty acids during the transition period will increase synthesis of PGF2∀. The linoleic fatty acids thus hasten uterine involution and reduce the incidence of clinical and subclinical uterine inflammation; which translates to increased fertility.
Fatty acids are obtained through conversion of glycerides by either hydrolysis or saponification. Because of their fragile stability and complex degradation kinetics, certain unsaturated fatty acids, such as omega-3 fatty acids, have been difficult to incorporate into acceptable and effective nutritional supplements that are easily manufactured.
While monovalent and divalent salts of saturated and unsaturated fatty acids have shown exceptional storage stability, unsaturated fatty acids typically do not readily react to form calcium salts using the processes known in the art such as those disclosed in U.S. Pat. Nos. 5,143,737, 4,642,317; 4,826,694; 4,853,233 and 4,909,138. Instead of forming free-flowing granules, a mass develops that hardens into a tough material that resists grinding into the fine particles required for manufacturing nutritional supplements. The resulting material also lacks storage stability. The product tends to auto-oxidize through an exothermic reaction that leads to a congealing of the product mass from its free flowing granular state to a hard amorphous state.
U.S. Pat. No. 6,576,667 discloses methods by which calcium salts of unsaturated fatty acids having as high as 60 percent by weight glycerides can be prepared. The disclosure of this patent is incorporated by reference. However, commercial sources of unsaturated fatty acids such as marine oils have glyceride contents as high as 100 percent by weight, which remain difficult to convert to storage stable free-flowing fatty acid divalent metal salts. U.S. Pat. No. 6,576,667 addresses this problem by diluting the high glyceride content oils to glyceride levels below 60 weight percent with lower glyceride content fatty acid feedstocks such as Palm Fatty Acid Distillates (PFAD's). However, this also reduces the unsaturated fatty acid concentration in the fatty acid calcium salt product, requiring greater quantities to be fed as part of a feed ration to adequately supplement the ruminant diet.
U.S. Pat. No. 6,229,031 discloses a saponification method by which calcium salts of fatty acids having as high as 100 percent by weight glycerides can be prepared. The disclosure of this patent is also incorporated by reference. However, calcium salts prepared from fatty acids with a significant degree of unsaturation prepared by this method have been discovered to lack storage stability.
A need exists for a method by which monovalent and divalent metal salts of unsaturated fatty acids having acceptable storage stability can be prepared.